Rotary well bits



March 8, 1966 s. R. KNAPP ROTARY WELL BITS Filed Feb. 21, 1963 FIG.I

D. W0. NO Wn NK d n O m y 0 R h I 8 S ATTORNEYS United States Patent ()1 3,239,431 ROTARY WELL BITS Seth Raymond Knapp, Box 385, Ardmore, Okla. Filed Feb. 21, 1963, Ser. No. 260,165 3 Claims. (Cl. 175-331) This invention relates to new and useful improvements in rotary well bits.

The invention is directed in particular to rotary well bits of the type having two or more cutter cones rotatably mounted on the bit, such bits usually having from two to four cutter cones.

It has long been a problem in the drilling of wells, and specifically in the drilling of petroleum wells several thousand or more'feet in depth, to preserve the vertical alinement'of the-well bore. All well bores deviate to some extent from st'rictvertical alinement, but in many instances the deviations are of such magnitude as to violate various' laws and regulations or to bottom the well bore-.ata point quite-considerably removed from the desired location. It is. a principal object of this invention to provide an improved rotary well bit which functions to minimize the deviation of the'well bore from vertical alinement.

To the best of my knowledge, the conventional rotary or cone type well bit has the rotational axes of its cutter cones disposed at an angi e of approximately 36 with respect to a plane passing perpendicularly to the longitudinal axis of the bit, and with the cones so angularly disposed, the lowermost points on the heels or outer marginal portions of the cones do not cut a full gauge well bore, but instead, the bore is reamed to full gauge by the action of the marginal portions of the cones at points displaced from the lowermost extremely thereof. It is also known that a drill bit must pass through varying formations and strata, many of which are inclined with respect to the horizontal or, at least, are not normal to the longitudinal axis of the well bore, and in passing from a hard formation to a softer formation, or vice versa, and where such formations are inclined with respect to the horizontal, the above described reaming action of the conventional bit causes the bit to tend to shift laterally, thus causing the well bore to assume a degree of angularity with respect to the vertical. Thus, it is a further principal object of the invention to provide an improved rotary well bit in which the tendency of the bit to shift laterally when passing from one formation to another, particularly inclined formations, is held to a minimum.

A further object of the invention is to provide an improved rotary well bit having a groove completely encircling the heel portions of all of the cutter cones of the bit so arranged as to maintain at all times a relatively sharp cutting edge on the heel or marginal portion of the cone which will cut a full gauge well bore and eliminate the need for any reaming action to maintain such full gauge.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing, wherein an example of the invention is shown, and wherein:

FIG. 1 is a vertical view, partly in elevation and partly in section illustrating a rotary well bit constructed in accordance with this invention, and

FIG. 2 is a bottom plan view of the well bit, the line 1-1 of FIG. 2 designating the line upon which FIG. 1 is taken.

In the drawing, the numeral designates the bit body having the usual upstanding, tapered, screwthreaded pin 1 for reception in the lower end of a drill string or drill "ice collar in the conventional fashion, there being provided the usual shoulder 12 between the pin 11 and the body 10 for abutment with the lower end of the drill collar. The drill body 10 has the usual central water course 13 which may be arranged in any suitable or desirable fashion and carries at least two and usually two to four depending shanks 14 for carrying the cutter cones. In the particular embodiment of the invention shown in the drawing, there are three of the depending shanks and thus three of the cutter cones.

Each of the shanks has suitably mounted therein a conventional trunion or spindle 15 upon which the cutter cones 16 are mounted by means of roller or other conventional bearings 17 and retaining rings 18. The structure and arrangement of the shanks, the spindles, the bearings and the cutter cone retaining means is not critical to the invention, and may be of any suitable or desirable design. It is, however, based empirically on my experience, important that the spindles 15 extend downwardly and inwardly toward the longitudinal axis of the drill bit at an angle of approximately 39 with respect to a plane passing through the drill bit perpendicular to the longitudinal axis therein as contrasted to the angle of approximately 36 normally employed in such bits.

The cutter cones 16 are of the usual configuration and carry a plurality of cutter members or means 19 on their conical surfaces for carrying out the bulk of the cutting or drilling action. Each of the cutter cones 16 has the usual apex 2i) and also a heel, base portion or marginal position 21 at the outer or lower extremity of each of the cutter cones.

The most important feature of the invention is the provision in each of the cutter cones 16 of the well bit of a marginal groove 22 extending circumferentially completely around the heel or base portion of each of the conical face of each of the cutter cones, the grooves 22 as shown in FIG. 1 being V-shaped in cross-section and having an outer face inclined at an angle, approximately in the embodiment shown, with respect to the longitudinal axis of the cutter cone, and an inner face extending more or less parallel to said axis. The outer face merges into the extreme marginal edges or heel portions of the conical faces of the cutter cones to form relatively sharp cutter edges 23, the lowermost portions of which, as shown in FIG. 1, are disposed at full well gauge or diameter. Thus, when the bit is being utilized in drilling, whatever points of the cutting edges 23 are momentarily disposed at the lowermost point in the well bore are spaced apart from one another by full well gauge or diameter so as to cut a full gauge hole without the necessity of any subsequent reaming action by other portions of the cutting edges 23 not at that time lowermost in the well bore. The V-shaped cross-section of the grooves 22 causes the cutting edges 23 to depend from a relatively heavy V-shaped section on the heels or marginal portions of the cutter cones, and the wearing action of the formation or strata being drilled or cut, functions to wear away slowly the outer faces of the grooves 22 and maintain the cutting edges 23 not only relatively sharp but at full well bore gauge or diameter. It has been found that the remaining of full bore gauge as well as the maintaining of the cutting edges 23 in the relatively sharp condition obviates the tendency of the drill bit to shift laterally when passing from one formatron to another, especially inclined formations, and thus preserves to a marked degree the straightness or trueness to a vertical axis of the well bore.

The inclined outer walls of the grooves 22 also function as wedges to dislodge or break off those portions of the formation over which the grooves pass and which are not cut or drilled by the cutter members 19.

The disposition of the axes of the cutter cones at an angle of approximately 39 is also an important feature of the invention in that this functions to maintain the lowermost points of the cutter edges 23 at full bore gauge or diameter rather than slightly thereunder as is the case with conventionaldrill bits. Thus, at its outermost and lowermost point or points of contact with the formation, the drill bit and the cutter cones thereof are at full bore gauge.

A further important feature of the invention is the maintaining of the upper portions of the shanks 14 at full bore gauge from their. bottom to their top ends, as

shown in FIG. 1, and the coating of the shanks 14 rigidity as well as the desired self-sharpening action for the cutter edges-23 and the maintaining of the bit in the proper vertical alinement, minimizing any tendency to shift laterally upon passing from one formation to another.

,Bits constructed in-accordance with this inventionhave been found to drill more nearly vertical well bores, and it has further been found that the .marginalcutting edges 23 are maintained in a relatively sharp condition substantially throughout the useful life of the drill bit.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A rotary well bit including a head, means onthe head for connecting the bit to means for rotating the bit in a well bore, at least two cutter shanks depending from the cutter shanks, each of the cutter cones having a con-:

ical cutting face and an outer base margin, each of the cutter cones having on its conical cutting face a plurality of discrete drilling elements spaced apart from. one an other both circumferentially and axially andqcovering substantially the entirecutting face, each of the cutter cones also having at the base of its conicalcutting face only a single circumferential groove or recess having inner and outer walls, the inner walls of the grooves being formed by the outermost drilling elements on the cutter cones, the outer walls of the grooves intersecting the base margins of the cutter cones to formrelatively sharp cutting edges extending circumferentially of the conical faces at said base margins and disposed radially outwardly of the drilling elements on the'cuttercones.

2. A rotary well bit as set forth in claim 1 wherein the grooves are V-shaped in cross+section.

3. A rotary well bit as set forth inclaim 1 wherein.

the lowermost portions-of said sharp cutting edges are spaced apart from one another :at full bit gauge.

References Cited by theExaminer UNITED STATESPPATENTS 1,143,271 6/1915 Hughes -378 X 1,551,366 8/1925 Carlson .175355 1,659,893 2/1928 Overrnan- 175364- 1,855,330 4/1932 Zublin 175-411 X- 2,851,253 9/1958 Boice 175355 JACOB L. NACKENOFF; Primary Examiner.

BENJAMIN BENDETT, CHARLES O7CONNELL,

7' QWW'EW: 

1. A ROTARY WELL BIT INCLUDING A HEAD, MEANS ON THE HEAD FOR CONNECTING THE BIT TO MEANS FOR ROTATING THE BIT IN A WELL BORE, AT LEAST TWO CUTTER SHANKS DEPENDING FROM THE HEAD AT AN ANGLE OF APPROXIMATELY 39* WITH RESPECT TO A PLANE AT RIGHT ANGLES TO THE LONGITUDINAL AXIS OF THE BIT, AND A CUTTER CONE REVOLVABLY MOUNTED ON EACH OF THE CUTTER SHANKS, EACH OF THE CUTTER CONES HAVING A CONICAL CUTTING FACE AND AN OUTER BASE MARGIN, EACH OF THE CUTTER CONES HAVING ON ITS CONICAL CUTTING FACE A PLURALITY OF DISCRETE DRILLING ELEMENTS SPACED APART FROM ONE ANOTHER BOTH CIRCUMFERENTIALLY AND AXIALLY AND COVERING SUBSTANTIALLY THE ENTIRE CUTTING FACE, EACH OF THE CUTTER CONES ALSO HAVING AT THE BASE OF ITS CONICAL CUTTING FACE ONLY A SINGLE CIRCUMFERENTIAL GROOVE OR RECESS HAVING INNER AND OUTER WALLS, THE INNER WALLS OF THE GROOVES BEING FORMED BY THE OUTERMOST DRILLING ELEMENTS ON THE CUTTER CONES, THE OUTER WALLS OF THE GROOVES INTERSECTING THE BASE MARGINS OF THE CUTTER CONES TO FORM RELATIVELY SHARP CUTTING EDGES EXTENDING CIRCUMFERENTIALLY OF THE CONICAL FACES AT SAID BASE MARGINS AND DISPOSED RADIALLY OUTWARDLY OF THE DRILLING ELEMENTS ON THE CUTTER CONES. 